CMSC 426 Exam 2 (Possible Questions All Solved)

Cryptography correct answers "Hidden writing" Creation and use of secret codes and data-related security measures Cryptanalysis correct answers Theory and practice of "breaking" cryptographic protocols "Breaking" means recovering protected text/bypassing security process a cryptanalyst uses in order to discover plaintext and/or secret key. Cryptology correct answers The study of coded messages Scientific study of codes: creating, using, analyzing, "breaking" Symmetric Encryption correct answers uses the same key to encrypt and decrypt data Asymmetric Encryption correct answers Uses different keys for encryption and decryption Ceaser Cipher correct answers Used by Julius Caesar "Rotation" of the alphabet, traditionally a shift of 3 Only 25 possible encryptions, easy to brute force Keyword Cipher correct answers Keyword "begins" the alphabet, rest follows in order SECRETBCDEFG For better security and readability, shown in 5 letter blocks Vigenere Cipher correct answers Keyword is repeated and is used to shift plaintext into cipher text SECURITY using DOGSDOGS = WTJNVXAR Simple Substitution Cipher correct answers Assume "alphabet" of 38 chars (A-Z, 0-9, " ", and .). The cipher is random, no keyword or simple reversal/shift of alphabet 38! permutations of 38 chars Substitution Cipher Examples correct answers Plaintext Ciphertext - both are a message written in 38-char alphabet Encryption algorithm - application of the substitution cipher to the original message Secret Key - the substitution ciphered alphabet